The invention relates to the field of information formatting useful for optical or magnetic disk or tape, optical or electronic signal transmission, or other information carriers.
An information carrier includes information arranged according to a recording format, the information being recorded according to predefined encoding rules and including format information indicative of parameters of the recording format.
A player for reproducing information from the information carrier, has format apparatus for providing parameters of the recording format, and reading apparatus for retrieving the information depending on the parameters of the recording format.
A recorder records information arranged according to a recording format on an information carrier, the recorder has recording apparatus for recording the information according to predefined encoding rules, the recorded information including format information indicating parameters of the recording format.
A method for recording information arranged according to a recording format on an information carrier includes recording the information according to predefined encoding rules, and format information is included indicating parameters of the recording format.
Those skilled in the art are directed to the following related documents:
(D1) U.S. Pat. No. 5,737,286 to Timmermans issued Apr. 7, 1998 for xe2x80x9cSystem And Apparatus For Recovering Information From A Record Carrier Which Exhibits Variations Of Two Different Physical Parameters Thereofxe2x80x9d.
(D2) WO 98/16014-A1 by Bruekers et. al. for xe2x80x9cdata Compression And Expansion Of An Audio Signalxe2x80x9d.
(D3) WO 98/33325-A2 by Linnartz et. al. for xe2x80x9cMethod and system for transferring content information and supplemental information relating theretoxe2x80x9d.
(D4) xe2x80x9cApplied cryptographyxe2x80x9d, by Bruce Schneider ISBN 0-471-12845-7 pp. 390-392.
A system for copy protection of recorded information including an information carrier, a player, and a recorder, is known from U.S. Pat. No. 5,737,286 (D1 of the list of relevant documents). Copy protection may include preventing the creation of a digital copy on a different carrier, allowing some copy activity (e.g. only a first generation of copies), or controlling, verifying or restricting the access to protected information. The information carrier includes information recorded according to an existing recording format, e.g. the CD-ROM format. The format prescribes the structure of recorded information, such as what type of information is recorded at which location on the disc, e.g. that the recorded area starts with a lead-in area at a predetermined diameter. Such a format may also include other parameters such as a type of recording layer (recordable, pre-recorded, etc), a number of recording layers and physical parameters of the recording process (density, reflectivity, etc). Format information, which gives actual values of parameters of the recording format used on an information carrier in question, is included in the recorded information on the record carrier, and is intended for use by the player when reproducing user information from the information carrier, e.g. format parameters in sector headers or a Table Of Contents (TOC) which includes information indicating where the user information starts and ends. The information on the information carrier is recorded according to predefined encoding rules, such as the channel code (EFM) for translating the user bytes into lengths of optically readable pits in the CD, and error coding and sector structuring rules. Such encoding rules are usually a predefined part of the recording format, and are not indicated in the format information recorded on the disc. The player for reproducing the information carrier includes reading apparatus for reading and decoding the recorded information according to the inverse of the encoding rules.
In the system of D1 the player and information carrier form a system for controlled information reproduction, in which reproduction of illegally copied information is counteracted. Copy protection has a long history in audio or video publishing. The presently installed base of equipment, in particular Personal Computers (PC) with audio/video cards, provide little protection against unauthorized copying. In any copy-protection scheme, the most difficult issue is that a pirate can always attempt to playback an original disc, treat the content as if it were an analog home recording and record this playback. However the best quality is only available when a digital copy can be made. For digital storage media such as Digital Compact Cassette (DCC), xe2x80x9ccopy bitsxe2x80x9d have been defined, which bits indicate a copyright status, e.g. xe2x80x9cno copy allowedxe2x80x9d, xe2x80x9cfree copyxe2x80x9d or xe2x80x9cone generation of copy allowedxe2x80x9d. Other copy bits may indicate that the medium storing the information must be a xe2x80x9cprofessionalxe2x80x9d medium manufactured by pressing and not a xe2x80x9crecordablexe2x80x9d disc. However such copy bits can easily be ignored by the pirate, e.g. using a PC as copy engine. Devices which do not obey the rules of a format are called xe2x80x98non-compliantxe2x80x99 devices.
The copy protection of the system known from D1 is based on a so-called medium mark, i.e. a physical mark representing a bitpattern indicating the copyright status of the medium, e.g. a xe2x80x9cprofessionalxe2x80x9d disk manufactured by pressing. The medium mark itself is not copyable or changeable by standard recording equipment and the bitpattern is to be verified by the compliant player and may even be required for reproduction, e.g. a descramble code for recovering information stored as scrambled information. On the record carrier of D1 information is recorded in the track in a predefined manner represented by optically readable patterns formed by variation of a first physical parameter, such as the height of the scanned surface. The medium mark is constituted by a variations of a second parameter of the track which are modulated according to the bitpattern, e.g. an excursion in a transverse direction of the track formed by a pregroove, also denoted as wobble. If the information of the known record carrier is copied xe2x80x9cbit-by-bitxe2x80x9d by a pirate on a writable information carrier using a non-compliant device, the information of this copy cannot be reproduced by a compliant player, because the copy does not include the medium mark corresponding to the illegally copied information. However detecting the medium mark and retrieving the bitpattern requires additional elements in the compliant player, whereas a compliant recorder preferably also detects any medium mark on a recordable disc. Hence, the known system for copy protection requires expensive and complex players and recorders.
The above citations are hereby incorporated herein in whole by reference.
It is an object of the invention to provide a system in which accessing and copying recorded information is controlled and which is less complex.
For this purpose, in the information carrier of the invention the encoding rules correspond to rules of a different recording format that prescribes a predefined location on the information carrier for recording the format information, the predefined location includes a confusion pattern and the format information is recorded at a second location different from the predefined location. The player as described in the opening paragraph has format apparatus arranged for detecting the recording format of the information carrier, and the format apparatus are arranged for supplying predefined parameters or for retrieving the format information from the second location when the recording format is detected. The recorder as described in the opening paragraph has recording apparatus arranged for recording a confusion pattern at the predefined location and for recording the format information at a second location different from the predefined location.
Existing, non-compliant read devices will try to read the format information from the predefined location, but will read the confusion pattern instead. This confusion pattern will cause the existing devices to stop reading, or to use wrong settings for the reading apparatus, which causes the reading process to malfunction. This has the effect, that existing devices are prevented from accessing copy protected audio/video information from the information carrier, because they cannot read the format information. Hence a digital copy cannot be made using non-compliant players or recorders, even if they are not aware of (or manipulated to disregard) any copy protection information bits. While the format information is hidden for existing players, it can be easily retrieved by the player according to the invention. This has the advantage, that the reading apparatus, although including complex decoding and error correction circuits, can be manufactured relatively cheap because substantially all components are common to existing players.
The invention is based on the recognition, that the format information must be available, but cannot be manipulated in non-compliant devices. By relocating the format information uncontrolled playback of copy protected discs by existing, non compliant devices; can be prevented. In particular, the reading and/or recording of format information cannot be controlled or manipulated by a pirate, because such steps are usually built in a control unit in the basic read or write engine. As an alternative to relocating the format information, it would be possible to change the predefined encoding rules of an existing recording system for copy protection purposes. This however increases the cost of a new copy protected recording system, because complex IC""s must be redesigned and produced specifically for the new players and recorders. So in practice the encoding rules must be equal to the encoding rules of an existing system, e.g. the Compact Disc (CD) or Digital Versatile Disc (DVD) system, and non-compliant devices including such encoding and decoding apparatus are available. A record carrier recorded with the encoding rules could be played back on a non-compliant device, e.g. on the PC, and manipulation of audio/video information would be possible. However by relocating the format information according to the invention, non-compliant players are prevented from uncontrolled playback, because they rely on the format information, such as the TOC in CD or Physical Format information in DVD, for accessing the audio/video information.
In a preferred embodiment of the system of the invention the second location is variably selected within a predefined area of the information carrier and/or in that the format information located at the second location is encrypted using an encryption key. Variably selected means that when an audio/video production is put on a master disc for mass reproduction, a specific second location for that production is selected randomly from the range of possible locations. Alternatively or in combination one encryption key is generated randomly for each new production. This has the advantage, that it is more difficult for a pirate to locate or retrieve the correct format information.